How to Manage Pests

UC Pest Management Guidelines

Almond

Peach Silver Mite

Scientific name: Aculus cornutus

(Reviewed 3/09, updated 11/12)

In this Guideline:

DESCRIPTION OF THE PEST

Peach silver mite is white or cream-colored and extremely small. The body is teardrop-shaped with four short legs at the larger (anterior) end. Because it is much smaller than other mites on almonds, a high-power hand lens (15X or higher) is needed to see it clearly.

DAMAGE

Peach silver mite is not usually damaging in almonds, although it can cause symptoms if populations build up to high levels on trees under 6 years old. Feeding by peach silver mite causes tiny chlorotic spots that give the leaf a silvery appearance, especially along the midvein of the upper leaf surface. Symptoms resemble thrips or leafhopper damage. Once higher temperatures occur in late spring, brown necrotic spots develop along leaf margins following silver mite feeding early in the season.

MANAGEMENT

For the most part, peach silver mite is usually considered beneficial to have in the orchard because it serves as a food source for mite predators. Unless peach silver mite numbers are high enough (hundreds to thousands per leaf) that defoliation is occurring, no treatment is necessary.

Common name		Amount/Acre**		R.E.I.+	P.H.I.+
(trade name)		(conc.)	(dilute)
				(hours)	(days)
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy and impact on natural enemies and honey bees. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read the label of the product being used.
A.	NARROW RANGE OIL#
	(Omni Supreme and others)	Label rates		See label	See label
	MODE OF ACTION: Contact including smothering and barrier effects.
	COMMENTS: Cover all parts of the tree. Will control low-to-moderate infestations. See Dormant Treatment Decision Table for rate to use based on % infested spurs. Check with certifier to determine which products are organically acceptable.
B.	WETTABLE SULFUR#	Label rates		24	0
	MODE OF ACTION: Unknown. An inorganic insecticide.
	COMMENTS: Check with your certifier to determine which products are organically acceptable.
C.	ABAMECTIN*
	(various)	Label rates		See label	See label
	MODE OF ACTION GROUP NUMBER1: 6
	COMMENTS: Apply with a horticultural oil according to label directions.
**	For dilute applications, rate is per 100 gal water to be applied in 300–500 gal water/acre, depending on the label; for concentrate applications, use 80–100 gal water/acre, or lower if the label allows.
*	Permit required from county agricultural commissioner for purchase or use.
+	Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of these two intervals is the minimum time that must elapse before harvest may occur.
#	Acceptable for use on organically grown produce.
1	Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

PUBLICATION

UC IPM Pest Management Guidelines: Almond
UC ANR Publication 3431

Insects and Mites

F. G. Zalom, Entomology, UC Davis
C. Pickel, UC IPM Program, UC Cooperative Extension, Sutter/Yuba counties
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
D. R. Haviland, UC IPM Program, UC Cooperative Extension, Kern County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
Acknowledgment for contributions to Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier
L. C. Hendricks, UC Cooperative Extension, Merced County
R. L. Coviello, UC Cooperative Extension, Fresno County
M. W. Freeman, UC Cooperative Extension, Fresno County

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